| This paper studies the influence of loess-mudstone interface characteristics(humidity,thickness and inclination)on slope stability.Through laboratory tests on undisturbed soil samples,the variation law of shear strength of loess and slip zone soil under different water contents is obtained.Based on this laboratory study,the characteristics of loess-mudstone interface landslide are analyzed.Considering the influence of repeated rainfall on slope humidity distribution,a slope model with humidity stratification is established.Geostudio is used to analyze the influence of changes in humidity,thickness and inclination angle of loess-mudstone interface on slope stability,and corresponding prevention measures are proposed.The paper obtains the following understanding:(1)The physical index and shear strength of undisturbed loess and slip zone soil are obtained through laboratory tests,providing relevant parameters for subsequent numerical simulation.The test results show that the shear strength of undisturbed loess decreases in the form of a power function with the increase of water content,and there is a critical water content.When the water content in the soil is lower than the critical water content,the shear strength is significantly affected by the water content.When the water content is higher than the critical water content,the shear strength changes slowly.Research on the properties of sliding zone soil shows that the cohesive force of sliding zone soil changes within a small range,while the internal friction angle gradually decreases with the increase of water content.(2)The homogeneous loess slope model is established by using finite element software Geostudio,and the moisture stratification of homogeneous slope and the characteristics of slope stability,pore water pressure and volume water content are analyzed under the condition of multiple rainfalls.Through analysis,it is concluded that the multiple rainfalls mainly affect the depth of the slope top of not more than 5m,and the shallow surface layer soil moisture content on the slope surface,and the obvious moisture stratification phenomenon occurs on the slope after a long time.For homogeneous loess slopes,the greater the rainfall intensity,the deeper the influence area on the water content of the slope body,and the change of pore water pressure causes the change of effective stress and shear strength value.However,under the condition of homogeneous loess slope model,the change of soil shear strength index caused by the change of water content is not considered.Therefore,based on the aboveresults,a slope model considering the moisture distribution in the loess layer is established,which can make the following stability analysis of loess-mudstone slope more realistic.(3)A loess-mudstone interface slope model considering moisture stratification of loess layer is established,the effects of moisture,thickness of weak layer and inclination angle on slope stability are analyzed.Calculation and analysis show that humidity changes have a great influence on slope stability,but compared with the loess layer humidity changes,the weak layer humidity changes have the greatest influence on slope stability.The greater the thickness of the soft layer on the contact surface,the lower the slope stability.For slopes with different contact angles,the stability is closely related to the slope angle.(4)Based on the results of the study,several effective treatment measures for loess-mudstone slopes are proposed.Taking the landslide of Tianshui Forging Machine Tool Plant as an example,the analysis method and prevention measures in this paper are applied.This paper has application and practical guiding significance for landslide analysis of loess-mudstone interface,proposes a modeling method considering moisture stratification,specifically studies the characteristics of loess-mudstone interface,and provides landslide engineering prevention measures. |
PDF Full Text Request